Interfacial Visco-Elasticity of Crude Oil - Brine: An Alternative EOR Mechanism in Smart Waterflooding
- Vladimir Alvarado (University of Wyoming) | Mehrnoosh Moradi Bidhendi (University of Wyoming) | Griselda Garcia-Olvera (University of Wyoming) | Brendon Morin (University of Wyoming) | John S. Oakey (University of Wyoming)
- Document ID
- Society of Petroleum Engineers
- SPE Improved Oil Recovery Symposium, 12-16 April, Tulsa, Oklahoma, USA
- Publication Date
- Document Type
- Conference Paper
- 2014. Society of Petroleum Engineers
- 4.3.4 Scale, 1.4.3 Fines Migration, 1.6.9 Coring, Fishing, 5.4.7 Chemical Flooding Methods (e.g., Polymer, Solvent, Nitrogen, Immiscible CO2, Surfactant, Vapex), 5.2.1 Phase Behavior and PVT Measurements, 1.8 Formation Damage, 5.8.7 Carbonate Reservoir, 5.2 Reservoir Fluid Dynamics, 4.3.3 Aspaltenes, 5.7.2 Recovery Factors, 5.4.1 Waterflooding, 4.1.5 Processing Equipment, 5.1 Reservoir Characterisation, 5.1.1 Exploration, Development, Structural Geology
- Low Salimity, Interfacial Elasticity, EOR, Smart Water, Engineered Water
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Injection of water with designed chemistry has been proposed as a novel enhanced-oil recovery (EOR) method and is referred to as low salinity and smart waterflooding, among other names. The plethora of names encompasses a family of EOR methods relying on modifying water chemistry to increase oil recovery. Despite successful laboratory experiments and field trials, underlying EOR mechanisms remain controversial and poorly understood. The majority of hypotheses proposed rely on rock-fluid interactions. Here, we propose an alternative fluid-fluid interaction mechanism, i.e. an increase in crude oil-water interfacial visco-elasticity upon injection of designed brine.
Crude oils from Wyoming were selected for their known interfacial response to water chemistry variation. Brines were prepared using analytic grade salts to test the effect of specific anions and cations. The ionic strength of the brines was modified by dilution with deionized water to achieve desired salinity. A battery of experiments to demonstrate the impact of dynamic interfacial visco-elasticity on recovery included double-wall ring interfacial visco-elasticity, dilational rheology, direct visualization in microfluidic devices and coreflooding experiments in Berea sandstone.
Interfacial rheological characterization shows that interfacial visco-elasticity generally increases as brine salinity is decreased, regardless of cations and anions in brine. However, the rate of elasticity buildup and the plateau value depend upon specific ions. Snap-off analysis in a microfluidic device demonstrates that increased visco-elasticity suppresses interfacial pinch-off and sustains a more continuous oil phase. This effect was examined in coreflooding experiments using sodium sulfate brines. Corefloods were designed to prevent wettability alteration by maintaining a low temperature (25 oC) and short aging times. Geochemical analysis provided in situ water chemistry needed to establish a direct link between water chemistry and oil displacement. Recovery and pressure responses directly correlate with interfacial elasticity, i.e. recovery factor is greater the larger the induced interfacial visco-elasticity.
Our results demonstrate that an overlooked effect of engineered waterflooding can serve as an alternative and more universal explanation of low-salinity or engineered waterflooding recovery. This new mechanism offers a direction to design water chemistry for optimized waterflooding recovery in engineered water chemistry processes and opens a new route to design EOR methods.
|File Size||1 MB||Number of Pages||17|